ABSTRACT
Gestational weight gain (GWG) is a normal and expected component of a healthy pregnancy; however, gaining too much or too little weight poses significant risks to maternal and fetal health including fetal under - or overgrowth, downstream obesity, and cardio-metabolic disease. Children born to mothers who exceed the Institute of Medicine GWG recommendations are significantly more likely to have higher birth weights, classify as large for gestational age (LGA) and develop overweight/obesity in infancy, childhood, and adulthood. Furthermore, rapid increases in infant growth weight trajectory, defined by weight-for-length (WFL), as early as six months of life are also associated with obesity in childhood.
Energy expenditure and energy intake are known contributors to weight management, have been identified as predictors of excess GWG (eGWG) and are mediators of metabolic dysregulation affecting maternal-fetal health, perhaps independently of eGWG. The ACOG and the Society of Obstetricians and Gynecologists of Canada/Canadian Society for Exercise Physiology (SOGC/CSEP) currently endorse exercising for 30-minute sessions four times a week during the prenatal period. However, the guidelines are currently being reviewed to update recommendations based on more recent literature.
A two-arm, parallel group randomized controlled trial (RCT; the Maternal Obesity Management (MOM) trial), was established to mediate GWG and prevent downstream child obesity. Adult pregnant women mean age 32.6 ± 4.4 years, with pre-gravid BMI > 18.5 kg/m2, between 12 and 20 weeks gestation were randomized into one of two groups: lifestyle intervention (n = 41) who received a structured physical activity (PA) and nutrition program in addition to the MOM trial healthy pregnancy handbook, or a standard clinical care control group (n = 35). The intervention took place throughout pregnancy (~ 6 mos.), with postpartum follow-up assessments on mother and child. GWG and PA were objectively measured at three-time points in pregnancy (prior to intervention, second trimester 26-28 weeks, third trimester 36-40 weeks). Offspring WFL was directly measured at 3 and 6 mos postpartum. We hypothesized that women who participated in the lifestyle intervention including regular PA with a structured prenatal exercise class in combination with a nutrition intervention would be more likely to have offspring follow a healthy growth trajectory as measured by offspring WFL z-score between 3 to 6 months of age
We assessed and compared PA which was directly measured at three time points throughout the study (baseline, second trimester between 26-28 weeks, and third trimester between 36-40 weeks gestation) using accelerometers and supported by PA recall for activities not captured by the accelerometer. Compliance to exercise classes was recorded by the instructor. Total GWG was calculated in kilograms, by subtracting weight measured at the first prenatal visit from the last visit as part of the study or last prenatal visit, before birth, to capture the full extent of GWG throughout pregnancy. GWG was also evaluated categorically based on being under, meeting, or exceeding the IOM GWG guidelines. Offspring neonatal birth weight was measured in grams as an absolute value and was obtained from antenatal obstetrical records. Infant birth weight was also evaluated categorically as small for gestational age (SGA), average for gestational age (AGA) or large for gestational age (LGA). Infant body length was collected using a tape measure; two measurements were taken to the nearest 0.5 cm and the mean value was taken as true. The tape measure method has been validated against a measuring board which found no statistically significant difference between the two methods.
There were no significant differences in GWG between intervention group and control group (mean difference = 0.3 kg, 95% CI, -2.5 – 3.1, p = 0.838). There were also no significant differences in moderate to vigorous physical activity (MVPA) during the second trimester (Z = -0.3408, p = 0.733) and the third trimester of pregnancy (Z = -0.0121, p = 0.9904). However, an increase in light PA from the first study visit in early pregnancy to the second study visit at the end of the second trimester was significantly associated with decreased final GWG in the intervention group, but not in the control group (p = 0.014). Furthermore, a Wilcoxon Rank-Sum Test indicated that the change in weight-for-length z-score from 3 months to 6 months was significantly lower in children born to mothers in the intervention group compared to the children in the control group Ws = 481.00, z = 2.67, p = 0.007. Although GWG did not change, an improved early growth trajectory for offspring born to women engaged in the intervention was observed supporting that early exposures to PA, even light PA, may play a role in downstream child growth and development.
Future research should further evaluate optimal tools and counselling techniques that help women make the best possible nutrition and PA choices throughout pregnancy in the best interest of maternal and child health.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/38743 |
| Date | 24 January 2019 |
| Creators | Dingwall-Harvey, Alysha |
| Contributors | Adamo, Kristi Bree |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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